Elastic force development

A more complete technical description of the consilient mechanisms of concern to biological energy conversion encompasses two distinct but interlinked physical processes of hydrophobic association and of elastic force development. The latter results from a generally applicable... 

Contractility as the Coupling of Hydrophobic Association and Elastic Force Development... 

The second point addresses the nature of elastic force development in relation to imder-standing efficient energy conversion. If the energy required for chain deformation during elastic force development becomes lost to other parts of the protein and to the surrounding water, then so too is efficient energy conversion lost. In other words, elastomeric force development on deformation in a protein-based machine followed by marked hysteresis on relaxation necessarily denotes an inefficient protein-based machine. 

The hydrophobic and elastic consilient mechanisms, two distinct but interlinked physical processes of hydrophobic association/dissocia-tion and elastic force development/relaxation, couple to achieve movement. In functional... 

Useful elastic force develops at the fixed ends of a chain segment when the motion within the backbone of the chain segment decreases as the result of a deformation such as an increase in... 

The focus has been on both aspects of the consilient mechanism (hydrophobic association/ dissociation and elastic force development/ relaxation) involved in the unique domain movement for electron transfer within Complex III. In what follows, the same aspect of hydrophobic association/dissociation of the consilient mechanism is proposed for facilitating proton gating. 

Hypothesis Efficient Production of Motion by Muscle Contraction Derives from the Hydrophobic and Elastic Consilient Mechanisms, Whereby Dephosphorylation Results in Hydrophobic Association Coupled to Near-ideal Elastic Force Development... 

S Evidence for Elastic Force Development Resulting from Hydrophobic Association... 

The operative component of the comprehensive hydrophobic effect arises from the competition between charged and oil-like groups. This was shown to result in a previously unknown repulsive force embodied within an interaction energy called an apolar-polar repulsive free energy of hydration, AG,p. During function, AG,p works in conjunction with elastic force development by the restriction of internal chain dynamics. These have been called the hydrophobic and elastic consilient mechanisms. In Chapters 6,7, and 8, these consilient mechanisms were demonstrated to be fundamental to understanding the functions of biology s proteins. 

The energy conversions that produce motion in living organisms consist of two distinct but interlinked physical processes of hydrophobic association and elastic force development, collectively referred to as consilient mechanisms in that they each provide a common groundwork of explanation. The association of oil-like domains, hydrophobic association, has been characterized in terms of the comprehensive hydrophobic effect (CHE), and elastic force development has been described in terms of the damping of internal chain dynamics on deformation, whether deformation occurs by extension, compression or solvent-mediated repulsion (see section E.4.1.2 and Figures E.3 and E.4, below). 

As noted by Ra5mient and coworkers, a number of flexible loops occur in the crossbridge, and we suggest that these are potential sources for elastic force development that results from hydrophobic association of the powerstroke (see Chapter 8, section 8.5.4.5). 

As Wasserman and Salemme (1990) included water molecules in their calculations, and an ordering of water molecules was found as the hydrophobic side chains became exposed on chain extension, they considered this decrease in solvent entropy as a possible source of the entropic elastic force. As will be shown below, solvent entropy change does not make a significant contribution to the entropic elastic force development during isometric contractions. 

Hydrophobic Association Effects Elastic Force Development by Extending (and Thereby Damping Internal Djmamics of) Interconnecting Chain Segments... 

Figure 10. Cartoon of the relationship between hydrophobic association and entropic elastic force development. Above A series of clam-shaped globular protein strung together by elastic bands with an equilibrium between open and hydrophobically associated closed states. Clearly, as the equilibrium shifts toward more closed states, the force, sustained by the interconnecting elastic segments, increases. Below Representation of the p-spiral structure of...

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